Sophisticated material handling systems have been developed in recent years and are now being put to use in so-called flexible manufacturing systems. Such a material handling system is often designed around a lift which is able to move longitudinally in an aisle between a pair of racks forming storage areas comprising a series of columns divided into storage locations, the lift having forks or the like which are extendable on either side in order to pick up materials which are stowed in the storage bays on pallets. The lift is controlled automatically and is arranged to retrieve articles from the storage bay and insert articles into the storage bays on command. This is the basis of an ASRS. One or more input and output areas are provided.
Adaptation of such a material handling system to a flexible manufacturing system involves the requirement for plural manufacturing or assembly stations to be provided, preferably immediately adjacent the storage racks, at the base of the columns of the racks. However, it is not sufficient merely for the lift to deposit material or articles at the base of the storage rack, since the manufacturing or assembly process will usually require the operator to work around the article and may involve the use of an external crane, for example, which will need to gain access to the assembly or manufacturing area. Thus, such an area needs to be provided externally, to one side of the storage rack and some means is therefore required to move materials or articles from the lowermost position in the columns of the storage rack to an adjacent area.
Whilst this has been achieved with the use of mechanically driven conveyors, the provision of such equipment dramatically increases the costs of the system, due to the need to provide such equipment at the base of each column of the storage rack, if the material handling system is to be fully integrated into a flexible manufacturing system. Furthermore, such extendable forks or conveyors are also bulky and, depending upon the materials or articles being handled, may be unnecessarily so, particularly when dealing with relatively small but massive or heavy articles.
A further problem is that of providing for delivery of different sized loads, the existing systems being inflexible in this regard.
The present invention sets out to overcome these problems in order to provide an effective solution to the problem of delivering materials or articles from a rack to a manufacturing station.